Describing the Geomorphological History of the Fourth of July Cirque in the Front Range, Colorado by Using Soil Dating, Lichenometry and Rock Weathering

Home , Lichenometry

Describing the geomorphological history of the Fourth of July cirque in the Front Range, Colorado by using soil dating, lichenometry and rock weathering

Name: Martijn Schwering Student number: 890307756130 Supervisor: dr.ir. AJAM (Arnaud) Temme

Abstract A better understanding of the reactions of glaciers to climatic changes can be used to calibrate climatic models and improve these models so that predictions about the distribution of climatic conditions in the future will be more accurate. In the Fourth of July cirque multiple glaciations have taken place during the last 30 000 years. The deposits in the study area range from glacial deposits, such as moraines, to slope landforms, such as mudflows and ramparts. The age and responsible process of deposition of some of the landforms are still under discussion in literature, this study resolves some of these issues. The geomorphological history of the Fourth of July cirque was described with the use of field reconstruction, soil dating, lichenometry and rock weathering. These three different relative dating methods were used because they are cheaper, easier and less time consuming than absolute dating techniques, such as cosmogenic radionuclide exposure dating, are. It has been investigated to which extent each of these methods can be used to describe the evolution of a landscape. Soil dating yielded relative ages for the different landforms that were in line with the field reconstruction. The amount of rock weathering unfortunately could not be used to obtain detailed relative age trends. Lichenometry could be used to some extent to differentiate landforms of different age. Most of the landforms were older than the maximum age of the lichen species used in this research though, which made this method only useful for a few younger landforms.

Table of contents I Introduction ...... 6 Objectives ...... 8 II Study area ...... 9 Location ...... 9 Climate ...... 9 Bedrock ...... 10 Glacial history ...... 10 Post-glacial landscape development ...... 11 III Materials and methods ...... 13 Field reconstruction ...... 13 Field work ...... 13 Soil dating ...... 14 Rock weathering ...... 18 Lichenometry ...... 18 Materials ...... 19 IV Results ...... 20 Field observations ...... 20 Soil dating ...... 27 Rock weathering ...... 31 Lichenometry ...... 34 V Discussion ...... 37 Post-glacial landscape development ...... 37 To which extent can the soil development index be used to describe the evolution of a landscape? ...... 37 To which extent can the amount of rock weathering be used to describe the evolution of a landscape? ...... 42 To which extent can lichenometry be used to describe the evolution of a landscape? ...... 43 What is the geomorphological history of the landscape in this study? ...... 46 VI Conclusion ...... 47 References ...... 48 Appendix I: Soil site and surface descriptions ...... 51 Appendix II: Rock site and surface descriptions and measurements ...... 52 Appendix III: Overview of soil characteristics, PDI and HDI values ...... 53

Table of figures Figure 1: Location of study area the Fourth of July valley...... 9 Figure 2: The study area...... 9 Figure 3: The main rock types in the Fourth of July cirque...... 10 Figure 4: Results of Mahaney...... 12 Figure 5: Results of Williams...... 12 Figure 6: The Fourth of July cirque with the landforms drawn in based upon field observations only...... 20 Figure 7: The biggest of the multiple terminal moraines present in the cirque...... 21 Figure 8: Landforms 2, 3 and 4...... 22 Figure 9: Rocks from landform 1 have fallen on top of landform 2...... 23 Figure 10: Stream patters on landform 4 are visible as little ridges (indicated with red lines) of rocks with gullies in between them...... 24 Figure 11: Landforms 4, 5, 7, 8 and 9...... 25 Figure 12: Locations of the soil pits...... 27 Figure 13: The value of the PDI for every soil pit...... 28 Figure 14: The value of the Development Index for every Bw horizon...... 29 Figure 15: pH difference between the Bw horizon and the C horizon (pH_C - pH_Bw)...... 30 Figure 16: Map with all the locations of the rocks that were measured...... 31 Figure 17: Average rebound values for the last 20 rocks that were measured...... 32 Figure 18: Age according to (Benedict, 1967) of the biggest R.Geographicum lichen thallus per rock...... 34 Figure 19: Lichen cover (in %) per rock...... 36 Figure 20: Maximum diameter R.Geographicum thalli measured on 50 moraines in the Indian Peaks area. The measurements fall into three broad size classes, suggesting three major periods of Little Ice Age glaciation ...... 44

Table of tables Table 1: Assumptions for values of soil properties of the parent material...... 16 Table 2: Materials used for the field work...... 19 Table 3: The PDI for every soil pit...... 28 Table 4: Average, maximum and median rebound values per landform...... 33 Table 5: Ages of the biggest R.Geographicum thalli for multiple rocks on landform 4, 1, 3 and 2. Also the average, maximum and median for every landform is listed...... 35 Table 6: Values for soil-profile and color indices of the soils (Birkeland et al., 1987) ...... 40 Table 7: Values of the PDI of the sites in (Birkeland et al., 1987), calculated according to the method used in this research ...... 40 Table 8:Summary of the geomorphological history of the Fourth of July cirque. The determined type of deposit, relative age and estimated absolute age and their confirmation by each of the three relative dating techniques ...... 46

I Introduction Attention is focussed on improving climate prediction models nowadays, with the changing climate and the unknown consequences of it. A better understanding of the effects of global and regional climate on the local environment can make climate models more accurate. Glaciers for one are sensitive to climate changes and research on the reactions of glaciers to climate change can help in predicting future climate changes (Oerlemans et al., 1998). A second reason for wanting to know and understand past glacial extents, timing and impacts on the landscape, is to improve and provide paleoclimate reconstructions and landscape evolution models (Fu et al., 2013).

The spatial and temporal extent of glaciers in the past can be reconstructed accurately nowadays. Ages of boulders on moraines and of glacially polished bedrock (Dühnforth and Anderson, 2011) can be calculated precisely, with dating techniques such as cosmogenic radionuclide exposure. Exposure to the atmosphere of these surfaces started after glacial retreat, the calculated ages thus correspond to the start of the deglaciation. The former glacial extent can be reconstructed, when it is known for every boulder and bedrock surface when it was first exposed to the atmosphere. The spatial extent of a glacier and the fluctuations in this extent are a proxy for the distribution of climatic conditions and changes in these conditions, since glaciers are sensitive to environmental change (Owen et al., 2009), (Solomon, 2007), (Winkler et al., 2010). However, responses of single glaciers to climate change are not representative for global changes (Winkler et al., 2010) and often not even for a whole mountain range (Fountain et al., 2009). Knowledge about the diversity in glacier response to climate changes on a regional scale can be used to determine the climatic conditions responsible for these changes with more reliability (Winkler et al., 2010). When reactions of glaciers to climatic changes are known, this information can be used to calibrate climatic models and improve these models so that predictions about the distribution of climatic conditions in the future will be more accurate (Böhlert et al., 2011), (Owen et al., 2009). In practice this means that changes in sea level, the hydrological cycle and in natural hazards as a results of the melting of glaciers can be predicted better (Owen et al., 2009).

The interaction between glaciers and their beds can be observed consistently in large-scale glacial landscapes (Egholm et al., 2012). U-shaped valleys, hanging valleys, bowl-shaped cirque valleys, sharp ridges and steep horns are typical landforms associated with glaciers (Egholm et al., 2012). Landforms provide information about the processes that shaped them and the feedback of those processes. The formation of landforms by glacial erosion during glaciation, but also the destabilizing impact of a melting glacier and the associated slope failures, form the landscape. The role of slope failures in denudational unloading and landscape evolution has not been excessively studied yet (Shroder Jr et al., 2011). Evaluation of the impact of deglaciation and the associated denudational unloading can provide new insights in the system and the initiation of slope failures. This knowledge can be used to reconstruct paleoclimates and paleolandscapes and improve landscape evolution models.

Landscape reconstruction is thus an important tool to improve our understanding of the consequences of climate change. Existing methods to determine ages of boulders and bedrock, are time consuming, relatively expensive and only big rock surfaces can be used. The objective of this study is to investigate to which extent easier, cheaper and less time consuming methods can be applied in high mountain valleys.

This study was executed in the Fourth of July valley in Colorado, which was selected because there have been multiple glaciations, there are distinctive post-glacial landforms present and the evolution of part of the valley landscape is still under discussion. Relative dating methods that were used and combined are: - Field reconstruction - Soil dating - Lichenometry - Rock hardness

Field reconstruction was done by describing the form, characteristics and position in the landscape of every landform and for the valley as a whole. From the field observations, the locations for the soil pits and for the lichen and rock hardness measurements were determined. The method of description, interpretation and comparison with literature of the field observations is more accurate in describing the geomorphological history than the other three methods are individually. The glaciations that have taken place and their associated landforms have been described in detail for neighbouring valleys. The combination of this knowledge with field observations makes this method the basis for the other three methods. Field reconstruction served as a method for checking to which extent the other three methods could be used to describe the evolution of the landscape. If conflicting results were found, field reconstruction was used to explain these differences.

Soil dating was done by digging and describing soil pits on all landforms. For every soil horizon the texture, colour, structure, pH, moist consistence, organic matter content and the presence of roots, clay films and pores has been determined. These soil characteristics change over time and by combining them a Soil Development Index (SDI) can be calculated according to (Harden, 1982).

The lichen and rock hardness measurements were done on the same rocks. Of multiple Rhizocarpon Geographicum thalli on a rock surface the diameter was measured. This species was selected because of its longevity. The size of the thallus is an indication for the age and this lichen species in particular can reach an age up to 3000 years (Benedict, 1967).

Rock hardness uses the fact that the amount of weathering of a rock increases with the time since exposure to the atmosphere. Weathering of the rock causes the hardness of the rock to decrease. The methods were chosen because both the soil development and the exposure time of rocks to the atmosphere, estimated by rock hardness and lichenometry, can be used to determine the relative age of glacial deposits (Benedict, 1967), (Ericson, 2004), (Karlstrom, 2000).

Not only will be investigated to which extent relative dating techniques can be used to describe the evolution of a landscape, the geomorphological history of the study area will be captured as exact and detailed as possible. The last glaciation in the Pleistocene and the smaller glacial advances in the Holocene had the biggest impact on the study area of this research. Processes initiated during or after deglaciation are responsible for most of the landforms in this high mountain area, besides the landforms created by the glaciers themselves. For every landform the underlying process or processes and the time of deposition should be known. To reach this goal the relative dating techniques and observations in the field will be combined.

OBJECTIVES The main research question of this study is: - To which extent can relative dating techniques be used to describe the evolution of a landscape? - What is the geomorphological history of the landscape in this study?

The sub research questions of this study are: - To which extent can the soil development index be used to describe the evolution of a landscape? - To which extent can the amount of rock weathering be used to describe the evolution of a landscape? - To which extent can lichenometry be used to describe the evolution of a landscape?

II Study area

LOCATION The study area is part of the Fourth of July valley that lies 14 kilometer north-east of Nederland, Colorado as can be seen in figure 1 and contains the Fourth of July cirque. The cirque lies east of the Continental Divide in a south-facing position between 3400 and 3600 meter elevation, north of the Fourth of July mine (Mahaney, 1973a). The study area is mapped in Figure 1, with the cirque in the north.

Figure 1: Location of study area the Fourth of July valley.

Figure 2: The study area.

CLIMATE Climate data from Niwot Ridge, 4 kilometer to the north of the Fourth of July valley and at similar altitude, is used. The climate is cold and dry with a mean annual precipitation of 658 mm and a mean annual temperature of -3.3 ˚C (Marr, 1961). The annual temperature range is high, the summers are cool and there is a low moisture availability. Furthermore windy conditions are often present in the valley, with an average wind on the Niwot Ridge of 8.5 m/s

and gust of 50 m/s or more in the winter months (Benedict, 1968). Snowbanks in the Fourth of July cirque are present all year, they are found in protected positions in the cirque (Mahaney, 1973a). The biggest part of the snow that falls in the winter is lost in the summer due to ablation in late spring and early summer (Mahaney, 1973a).

BEDROCK Most of the bedrock in the Front Range of the Colorado Rocky mountains is igneous and metamorphic (Lovering and Goddard 1950, Tweto 1979, Braddock and Cole 1990). The main types of bedrock in the Fourth of July cirque itself (Levering and Goddard, 1950) are gneisses and schists.

Figure 3: The main rock types in the Fourth of July cirque.

GLACIAL HISTORY In the late Pleistocene there have been three major glaciations in the Rocky Mountains; the Pre-Bull Lake, Bull Lake and Pinedale glaciations (Janke 2005). This study will focus on the Holocene and the last glaciation in the Pleistocene; the Pinedale glaciation, that started at 30 kiloannum (ka) before present (B.P.) and reached its maximum around 23 ka B.P. (Nelson et al. 1979, Madole 1986, Caine 2001). Glaciers decreased in size from 23 ka B.P. onward until more rapid deglaciation started at 13 ka B.P. (Harbor 1984, Madole 1986). Nowadays two small glaciers exist in the Boulder Creek watershed; the Arikaree (0.06 km2 ) and the Arapaho (0.24 km2 ) glaciers (Dühnforth and Anderson 2011). The small sizes of the glaciers indicate that current conditions do not make larger glaciations possible. The two glaciers exist due to a combination of topographic shading, wind-blown snow accumulation and cold high-elevation temperatures (Dühnforth and Anderson 2011).

Since the Pinedale glaciation four minor glacial advances have taken place in the Holocene, the Satanta Peak (10 000-12 000 years B.P.) , Triple Lakes (3 000-5 200 years B.P.) Audubon (950-2 400 years B.P.) and Gannet Peak (100-350 years B.P.) (Birkeland et al., 1987). The names of these advances are informal (Birkeland et al., 1987), because they are allostratigraphic units according to the North American Commission on Stratigraphic Nomenclature (Nomenclature and Geologists, 1983). With the help of relative dating and radiocarbon dating, rock glaciers and moraines were dated and these four minor glacial advances were interpreted (Benedict, 1973). The ages of Gannet Peak, Audubon and Triple Lakes advances are agreed upon widely according to (Birkeland et al., 1987). The age of the Satanta Peak advance is not agreed upon by all workers though (Birkeland et al., 1987).

POST-GLACIAL LANDSCAPE DEVELOPMENT The post-glacial landscape development of the Fourth of July cirque has been under discussion. (Mahaney, 1973a) was the first to study the deposits using lichenometry, soil development, vegetation cover and weathering features. In figure 4 the results of Mahaney are mapped. He concluded that landform T1 is an end moraine of Triple Lake age and that landform Am is a mudflow of Audubon age. (Williams, 1973) did a study after Mahaney and came with an alternative interpretation and chronology of the Fourth of July cirque evolution. In figure 5 the results of her research are mapped. She concluded that Unit I is the oldest terminal moraine, of Bull Lake age. Within Unit II, landform rg is a rock glacier and landform pr is a protalus rampart, both of Pinedale age. Within Unit III landform m is an end moraine of Late Pinedale age and landform rg is a rock glacier of Late Pinedale age. The rest of the deposits in the cirque are of Gannet Peak age and the deposits above the rock glacier of Unit III are rock glaciers of Triple Lake age.

(Williams, 1973) and (Mahaney, 1973a) thus have some differences in their interpretation of the history of the Fourth of July cirque. - While Mahaney thinks the landform Am in figure 4 is a mudflow, Williams think the landform consists of two rock glaciers. In a response to Williams, Mahaney gives arguments for his interpretation in (Mahaney, 1973b). He says the lobate-tongue form and levees point to a mudflow. Rock glaciers are coarse-textured masses of debris, extending to the cirque headwalls, they usually have an ice core and often lack soil cover and vegetation (Mahaney, 1973b). (Williams, 1973) does not give any arguments for the landform being a rock glacier, she only says she came to that conclusion using aerial photographs and field observations. - The oldest lobe of the mudflow/rock glacier is older than the Unit III moraine according to Williams, while Mahaney states the lobe is younger than moraine. The lobe seems to be partly covered by the moraine according to Williams and should be older than the moraine according to the principle of superposition. - Unit I is a terminal moraine according to Williams, while Mahaney states it is a ground moraine. (Williams, 1973) says that the description of the late Bull Lake moraines (commonly large with smooth slopes and broadly breached tributary sytems) fits the description of this landform. (Mahaney, 1973b) says that the soil profile is similar to post-Pinedale soil profiles. Also the terminal moraine near Nederland, Colorado proves that large extensive glaciers were present in the Pinedale glacial. Glaciers in the Pinedale reached an height higher than the Fourth of July Cirque floor, which makes an terminal moraine of Bull Lake age impossible. - Furthermore their dating of the deposits differs ten thousands of years. (Mahaney, 1973b) predominantly relates this to differences in sampling.

Figure 4: Results of Mahaney.

Figure 5: Results of Williams.

III Materials and methods

FIELD RECONSTRUCTION Data has been collected in the field in seven whole days. The first two days general observations of the study area were made. These field observations were interpreted and compared with literature and landforms were classified. From these first observations the locations for the soil pits and rock measurements were determined. The locations were chosen to cover the range of landforms. Depending on the size of the landform and the time available for fieldwork, a minimum of one measurement and a maximum of eight measurements per landform was done. Observations in the field and the interpretation of these observations can rule out results from the other methods. This method was used to validate to which extent the other methods can be used and to describe the geomorphological history of the study area.

FIELD WORK

Soils A total of 34 pits were dug, of which 33 are located in the study area. The additional pit was dug on the Pinedale terminal moraine near Nederland, Colorado. The soil pits were dug until the unweathered parent material was reached. In 11 pits the parent material according to FAO guidelines (Jahn et al., 2006) was not reached. In some of the calculations of the SDI therefore assumptions had to be made with regard to the properties of the parent material.

Soil properties were described in the field and include; texture, color (hue, value and chroma), structure, pH, moist consistence, organic matter content and the presence of roots, clay films and pores. Most of these properties change as the soil develops. The texture of a soil becomes finer over time. Color hues become redder and chromas become brighter, which is called rubification (Harden, 1982). Since the soils in the study area have a sandy to gravelly texture, the presence of any structure at all can be an indication for age. If a structure is present in the soil, the consistence of this structure will be higher if the soil is older. The organic matter content in a soil increases when a soil ages. When soil organic matter (SOM) accumulates the soil becomes darker, this is called melanization (Harden, 1982). The pH depends on the leaching of cations: older soils will have a lower pH. The acidic rocks in the Fourth of July cirque have a pH around 6 and as the rock weathers and a soil is developed in the weathered rock, cations will leach and the pH will become lower. The presence and amount of roots and pores is especially important to know to be sure that the development of soils is caused by differences in age and not by differences in vegetation and/or biota.

Besides the description of these properties in the field also the surface characteristics were described. The type of vegetation and coverage, the landform in which the pit is located, the slope, the aspect, the profile and plan curvature, the surface stoniness, erosion features, GPS coördinates and any other additional information was noted. Also pictures were taken from both the surface and the pit.

Rock observations On total of 40 rocks the rock hardness and lichenometry measurements were done. Observations and measurements include; rock hardness, rock size, rock type, lichen coverage,

Rhizocarpon Geographicum coverage and Rhizocarpon Geographicum diameters. Rock hardness was measured with the Silverschmidt ST from Proceq.

Determination of the locations of the rocks is important. Areas subject to surging glaciers and reworking of moraines by debris flows are likely to be problematic. Moraines constructed in areas of debris flow activity will inevitably contain boulders of various ages, comprising both those released from older features and those released directly by the receding glacier (Goudie, 2006). Rocks that have probably been in situ since deglaciation are wanted. Therefore rocks that are on top of a moraine ridge, incorporated in the soil or on top of a landform far from any slopes were chosen. The probability that these rocks have been transported there by other processes than the process that formed the landform is small. The position of the rock on the landform and the size of the rock are important. When the rock is not incorporated in the soil but lies on the ridge of a landform, the biggest rock is chosen. For rocks incorporated in a soil, the surface had to be around 0.5 m2 in order to be able to do at least 15 rock hardness measurements.

The five biggest thalli on every rock were measured. If there was doubt whether the thalli were grown together, they were not measured. Besides writing down the size of every thallus also pictures of the rock were taken and characteristics were described. The side of exposure on a rock can be important for the size of a thallus (Benedict, 1967), therefore side characteristics were noted.

Rock hardness was determined after thalli measurements. Either 15 or 30 rock hardness measurements were taken, dependent on the size of the rock. When a rock is only 0.5 m3 it is almost impossible to do 30 measurement since measurements have to be about 2 cm apart to avoid measuring the same spots more than once. Therefore 30 measurements were done on rocks bigger than 4.5 m3 and 15 measurement were done on rocks bigger than 0.125 m3 and smaller than 4.5 m3. The measurements were done on every side of the rock in order to get a good distribution of measurements and a representative average.

SOIL DATING To determine the relative order of age of the soils in the valley, the soil development index (SDI) was used (Harden, 1982). This method was used because it is particularly difficult to come to a soil chronosequence in glaciated and tectonically active mountain areas. Glacial deposits are often spatially separated over different altitudes due to the fluctuation of the equilibrium line altitude (ELA) (Swanson et al., 1993). Factors as climate and vegetation are often changing with elevation. Therefore a soil chronosequence is hard to establish (Swanson et al., 1993). Since a sequence of soils of different age is not so obvious in this area, the SDI is used to determine the relative ages of the soils. The SDI is a combination of different field properties and gives an indication of the degree of soil development. Soil properties are converted into numeric data and are compared to their state in the parent material. Soil development is determined by different factors, the most important being parent material, topography, vegetation, climate and time (Birkeland et al., 2003). If all factors are constant except for the time of soil formation, the SDI can be coupled to the age of a soil. Multiple studies used the amount of soil development to get relative ages of glacial landforms in the Western United States (Douglass and Mickelson, 2007).

In the Fourth of July cirque some of the soil forming factors are the same for the entire area. The vegetation is grassy with some bushes on most landforms. Since the study area is small and has a maximum elevation difference of 200 m, the climate is constant. In the method of Harden the properties for every horizon are compared to the parent material, which also eliminates the influence of differences in parent material on the soil development. The only two factors that are not constant for every landform are the time since deposition and the topography. The topography is comparable for most landforms, but not for all landforms and these differences were taken into account in the interpretation of the results.

For interpretation of the results of the soil development indices the field reconstruction was taken into account. Observations in the field can exclude the results of this method. The SDI can be used to yield relative ages for landforms when the results are in agreement with the field reconstruction. When the results are conflicting it is often due to differences in one of the other soil forming factors than time. In the field reconstruction the other soil forming factors were described and the method can therefore be used to explain conflicting or unexpected results.

Laboratory work Some soil properties were established in the laboratory. First all soil samples were dried in aluminium tins in an oven for 3 hours on a temperature of 110 ˚C to make sure all water had evaporated. After the soil samples were dried they were crushed with a mortar and testle and sieved with a 2 mm sieve to separate the sand, clay and silt from the gravels and stones. From the remaining soil the organic matter (OM) content, pH and texture was determined.

The OM content was measured with the standard Loss-On-Ignition (LOI) method as described by (Blume et al., 1990). For each sample 5 gram of soil was ashed in a muffle furnace to remove the organic material. The difference in weight before and after LOI was used to calculate the organic matter content.

( )

OM = Organic Matter content in % b = weight of the soil sample before LOI in gram a = weight of the soil sample after LOI in gram

The pH was measured with a YSI 63 pH instrument, according to the field-moist pH determination method as described by (Blume et al., 1990). After calibration of the pH meter, 30 mL of water and 15 grams of soil were added in a plastic tube of 100 mL and mixed. After waiting for stabilization of the pH meter both the pH and the temperature were written down.

The texture was determined with dry sieving. By sieving the oven dried soil samples with a 0.063 mm and a 0.050 mm sieve the silt and clay fraction are separated from the sand fraction. The samples were sieved with both a 0.063 mm sieve and a 0.050 mm sieve because the distinction between the sand and the silt fraction is not universally agreed upon. Because of the low percentage of clay and silt in every soil sample the amounts of silt and clay could not be determined separately. Every soil sample was sieved for 5 minutes in a shaker with an amplitude of 4 to make sure all silt and clay is sieved out of the sand. In the final step the fraction bigger than 0.063 mm, the fraction between 0.050 mm and 0.063 mm and the fraction

smaller than 0.050 mm were weighted. From this texture analysis the texture class for every soil horizon was determined. The differences between the fraction of soil that passed through the 0.063 mm sieve and the 0.050 mm sieve were too small to make any difference for the texture class.

SDI calculation For every horizon, a soil development was calculated according to (Harden, 1982). The soil characteristics that were incorporated are the soil colour, melanization, structure, pH and texture. Other characteristics that were also measured and/or observed in the field that would be incorporated in the calculations are the dry and moist consistence and the presence of clay films. The consistence is not in the calculation of the SDI because there was almost no difference between the horizons and soils. The presence of clay films was not possible to determine and therefore also left out of the SDI.

The value for every property in a soil horizon was compared to the value of that property in the parent material. For the soil profiles that were not dug deep enough to reach the parent material assumptions for the soil properties were made. The assumptions were made on the basis of the values of the characteristics of parent material found in other profiles. In Table 1 the assumption values for every soil property can be found.

Table 1: Assumptions for values of soil properties of the parent material. SOIL PARENT PROPERTY MATERIAL colour 10yr 4/4 structure weak granular pH 4.5 texture sand

The five soil properties were quantified and normalized as described by (Harden, 1982). This method consists of the following steps: 1. Quantification of every soil property. A certain amount of points is given for a difference between the value of the property in the soil horizon in comparison to the parent material. 2. Normalization of every quantified soil property. The quantified property is divided by a given maximum. This maximum is different for every soil property. 3. All the normalized soil properties per soil horizon are added up. 4. The value of step 3 is divided by the number of soil properties, 5 in this case. 5. The value of step 4 is multiplied with the thickness of the soil horizon, this yields the Horizon Development Index. 6. The horizon development indices for every soil are added up, which yields a Profile Development Index.

The formula for the calculation of the PDI is given below:

∑

PDI = Profile Development Index i = soil horizon j = soil characteristic Q = the quantified value of the soil characteristic D = thickness of the soil horizon

The maximum of points that could be given for the rubification has been divided by two because only the moist colour has been determined. The other maxima were used as they were described by (Harden, 1982). The PDI that follows from this calculation is a relative index for the age. The higher the PDI is, the more developed the soil is. Not only the PDI was mapped, but also the HDI of every Bw horizon and the pH difference between the Bw and the C horizon. Because the pH can be determined accurately and is one of the most important indicators of development, these results were discussed separately.

ROCK WEATHERING The Schmidt hammer (McCarroll, 1994) was used to obtain quantitative relative information about the degree of rock weathering. This relative dating method is based on the progressive weathering of rock surfaces after exposure (Matthews and Shakesby, 1984). This means in general that the older a rock surface is, the more this surface is weathered. The amount of rebound of a surface is measured with the hammer, which is a measure for the hardness and degree of weathering (Walker, 2005). The hardness of a rock surface depends on the mechanical strength (Ericson 2004), that declines with increased weathering (Boelhouwers et al., 1999). Higher rebound values thus refer to younger deposits (Day, 1980), (McCarroll, 1989). Rock weathering is dependent not only on age but also on local climate, altitude, aspect and bedrock composition (Walker, 2005), which complicates the use of this technique.

Some advantages of the Schmidt hammer are that it is; a portable and cost effective tool, able to make readings in the field that are directly converted to a general measure for strength (compressive strength) and it is non-destructive (Aoki and Matsukura, 2007), (Goudie, 2006). Disadvantages could be that if the hammer is applied to a weak rock surface, the plunger tip will penetrate the material too far and no accurate and reliable readings will be provided (Aoki and Matsukura, 2007). Also rock surfaces have to be of a minimum size to be measured (Goudie, 2006); the suggested minimum size to get precise and consistent rebound values for a block is 25 kilograms (Sumner et al., 2002). Irregularities, discontinuities and differences in moisture content of a rock can also influence Schmidt hammer results (Goudie, 2006).

LICHENOMETRY The principle of lichenometry is that the largest lichen body or thallus on a rock surface is representative for the time since exposure to colonization and growth of lichens on that rock surface (Benedict, 1967). There are more factors influencing the size of a lichen body though, such as the micro-environment and long term differences in regional climate. In the micro- environment moisture, stability of the rock or the surface on which the lichen is growing and length of snow-free growing season have the biggest influence on the actual size of the lichens (Benedict, 1967). The application, problems and basic ideas of lichenometry in geomorphological research have already been discussed by many researchers (Benedict, 1967), (Mahaney, 1973a). The main conclusion is that lichenometry can be used to date deposits up to a certain age, when problem areas are avoided. For the species used in this study, the Rhizocarpon Geographicum, surfaces up to 3000 years old can be dated. The application of the method should be restricted to granitic rock types on sites that become snow-free by late spring or early summer (Benedict 1967). Sites that are moist should be avoided (Benedict 1967).

The lichen species that was used in this research is the Rhizocarpon Geographicum. This species was chosen because it can date back deposits up to an age of 3 000 years old (Benedict, 1967), (Benedict, 1968). Other lichen species can only be used for dating of deposits that are a few decades or a few ages old.

Determination of the R.Geographicum can be difficult because the other species in the Rhizocarpon family that are also present in the study area look alike, which makes distinguishing between them hard. In accordance with procedures used by (Benedict, 1967) it was not attempted to distinguish between the subspecies in order to keep the method usable in the field. The yellow Rhizocarpons have been measured in the field. This probably means that

not only R.Geographicum has been measured but also other species. Since the R.Geographicum is the most common Rhizocarpon, grows faster than other species (Benedict, 1967) and only the biggest thalli were measured, most of the measured thalli will be R.Geographicum.

Ages for the rocks based on the biggest thallus on that rock were calculated with the lichen- growth curve as described in (Benedict, 1967), see the formula given below. Ages were rounded up because this method is accurate up to approximately 50 years.

( )

Age = age of the Rhizocarpon Geographicum thallus D = diameter of the Rhizocarpon Geographicum thallus

MATERIALS Materials that are required for the methods described above are listed in Table 2.

Table 2: Materials used for the field work. GPS Compass Inclinometer Tape measure Geological hammer Stone guide FAO soil description guidelines (FAO, 2006) Munsell color charts Pickaxe Water bottle Spade Magnifying-glass Silverschmidt ST

IV Results

FIELD OBSERVATIONS The Fourth of July cirque area is shaped as a hanging valley; a relatively flat surface area with steep slopes into the main Fourth of July valley. The cirque is located in the northwest of the study area with southeast exposure and with ice-fields present even in the summer. Figure 6 presents the landforms that were classified and described. For the remaining parts of the study area no landforms could be distinguished.

Figure 6: The Fourth of July cirque with the landforms drawn in based upon field observations only.

Landform 1 The landform has a clear half-moon shape with steep slopes consisting of rocks. Multiple smaller landforms of similar shape can be distinguished higher, on the inside of the half- moon. The biggest of these landforms is furthest away from the cirque and has more material on one side than on the other side. Behind it and in front of the smaller landforms, a soil with a thickness of more than two meters is found. The soil consists of alternating finer and coarser sediment. Some rocks do not have any vegetation or lichen cover.

Figure 7: The biggest of the multiple terminal moraines present in the cirque.

The landform consist of multiple end moraines created by glacial advances and retreats, the biggest one can be seen in Figure 7. The presence of more rocks on one side than the other can be due to the dropping of rocks from the side walls on the glacier and the transportation of these rocks to the front of the glacier. Grey rocks without any lichens/vegetation do not indicate more recent deposition but are still covered by ice/snow every year, so there is no chance for lichens to grow. The finely layered soil behind the biggest end moraine indicates that a small lake was present, which is observed behind other terminal moraines in the Front Range as well (Benedict, 1968).

Figure 8: Landforms 2, 3 and 4.

Landform 2 Landform 2 and 3 are two different landforms, since 3 seems to be on top of a part of 2 as can

be seen in Figure 8. Landform 2 has a ring of rocks with a small lake behind it.

Landform 2 can be either a rock glacier, a mudflow or another type of slope landform. The matrix of rocks with soil in between it and the ring of rocks with the depression and the small lake behind it could be more in favour of a rock glacier than a mudflow. When the ice core in a rock glacier melts the smaller rocks, that are in the middle of the rock glacier, collapse, leaving the bigger rocks on the sides sticking out as a ring. Most rock glaciers do not have such a pronounced ring of rocks as is the case for landform 2 though. Comparing the

landform to other known slope landforms, the ring of big rocks and the depression behind it indicates that it could be a rampart. When rocks roll over a slope and are deposited at the foot slope, a rampart is created. Landform 2 probably is a rampart because of its shape and the matrix of rocks with soil in between those rocks.

Whether or not landform 2 is older than landform 1 is open for discussion. The following arguments apply:  less lichens on landform 1, so landform 1 is younger  rocks of landform 1 seem to have fallen on landform 2, so landform 1 is younger or rocks have fallen after the deposition of landform 2  landform 2 seems to have flowed along the moraine that was already present, three options: o coincidence o the glacier that deposited landform 1 was influenced by landform 2 and did not advance further because of landform 2 o landform 2 was influenced by landform 1 and flowed along it

Figure 9: Rocks from landform 1 have fallen on top of landform 2.

Rocks have fallen from landform 1 on landform 2 as can be seen in figure 9. It was not visible in the field if one landform is on top of the other. Landform 1 seems to be on top of landform 2 when looking at the hillshades of the area. If this is true, landform 1 is younger because of the principle of superposition. It is also too much of a coincidence that landform 2 was deposited in this location against landform 1. Landform 2 is therefore possibly older than landform 1.

Figure 10: Stream patters on landform 4 are visible as little ridges (indicated with red lines) of rocks with gullies in between them.

Landform 3 Patterned ground and relatively small rocks on the surface without vegetation, located on the sides of the landform. Rocks are not pointy but flat. Stream patterns are visible, little ridges of rocks with gullies in between them as can be seen in Figure 10. Also this landform has more fine-earth than landform 2 and is tongue shaped, therefore it probably is a mudflow. The origin of the mud is open for discussion and can only be speculated upon.

Landform 4 This part of the study area is flat and wet, with groundwater at the surface in the form of small lakes and streams. Rocks present are mostly flat, probably because the glacier was on top of them. This landform is probably a ground moraine because of these reasons.

Figure 11: Landforms 4, 5, 7, 8 and 9.

Landform 5 On the bottom of the study area, directly against the deeper valley of the 4th of July valley, there is a flat ridge. Landform 5 probably is a lateral moraine. The glacier in the study area and the glacier in the 4th of July valley were probably pushed together and the glaciers joined further down east. The entire study area is a hanging valley which is indicated by the sudden drop from the relatively flat ground moraine into the deeper lying Fourth of July valley. In figure 11 the flat, wet ground moraine (4) and the lateral moraine (5) can be seen. The clear end towards the bigger Fourth of July valley is the end of the hanging valley.

Landform 6 This landform consists of rocks that clearly came down from the Quarter to Five peak. The ring of rocks with the depression behind it indicate that landform 6 is a rampart. Behind the rampart are more recently deposited rocks without any lichens or weathering features, which

indicates that the slope processes on this location are still active or have been active until recently.

Landform 7 This ‘hill’ or ‘bulb’ in the landscape has a higher elevation than the surrounding landforms.

There has probably not been a glacier on top of this hill, because the top of the glacier never reached this elevation. In (Ward et al., 2009) the absolute ages for several rock surfaces have been determined. Sample number 33-JB-30 at an elevation of 3422 meter has an exposure time of 16 221 years. Directly above this sample at an elevation of 3464 meter sample number JB03-29 was taken, this sample has an exposure time of 42 493 years and was therefore not glaciated in the Pinedale. The top of the glacier was somewhere in between those points. The slope of the Fourth of July valley was approximated in Google Earth and is 3.54 degrees. The distance between the samples taken by (Ward et al., 2009) and the study area of this research is 2000 meter. By taking an height of 3443 in between the two samples and interpolating this height over a distance of 2000 meter with a slope of 3.54 degrees yields an elevation of 3567 meter, this is the height the Pinedale glacier could have reached. The minimum height the glacier could have reached is 3443 meter, which is the height of the glacier under the assumption of a 0 degree slope. The elevation of the bedrock hill is 3530 meter. It thus possible that the Pinedale glacier has never been on top of the bedrock hill. It is however not excluded that the glacier was on top of the hill, since it could have potentially reached an elevation of 3567 meter.

Landform 8 This landform lies against the bedrock hill and has a lot of flat stones in the top soil.

Because of these flat stones it could be a ground moraine but because of the shape and higher elevation above landform 4 it could also be a lateral moraine. Landform 8 might be somewhere in between those two moraines and could be called a transitional moraine. No clear classification based on field observations could be made though.

Landform 9 In between landform 4 and landform 8 is a landform with a lot of boulders. Part of these boulders is completely free of vegetation/lichens and soil, probably because of snow coverage in the winter. The other part of the landform is located at the foot of landform 8, with some soil and a lot of trees.

The high amount of boulders and lack of vegetation/lichens and soil indicates that this landform probably is a blockflow that came down from the slope above landform 10 and 11.

Landform 10 This landform consists of a high, steep wall of rocks and soil on the east and south side. In the middle of the landform stream patterns are visible and it looks like the middle portion of the landform has been deposited here later than the surrounding higher walls.

Landform 11 A lobe of rocks near the headwall of the valley without any vegetation/lichens.

Probably an active or recently deactivated rock glacier near the bedrock wall of the study area. The rocks are not covered with lichens and the rock glacier has not collapsed yet. It was not checked if landform 11 still had an ice-core, so it is not possible to say if it still active.

SOIL DATING In Figure 12 the locations of the soil pits are mapped. Only pit number 19 is not visible since it is located on the Pinedale terminal moraine near Nederland. Soils were described on every landform.

In Appendix I the site and surface descriptions of the soil pits are listed in a table. In Appendix III the soil characteristics that were used to calculate the SDI for every soil pit can be found.

Figure 12: Locations of the soil pits.

Figure 13: The value of the PDI for every soil pit.

In Figure 13 the Profile Development Index (PDI) for every soil pit is mapped. The lowest values for the PDI are found on landform 10, on the end moraines near the cirque (landform 1) and on landforms 2 and 3. The highest PDI’s can be found on the lateral moraine (landform 5), the bedrock hill (landform 8) and the locations surrounding the hill. Table 3 contains the PDI for every soil. The variation of the PDI within one landform is limited for most landforms. For some landforms the variation is high though, this is the case for landform 4 for example. The possible reasons for these differences and the conclusion about the suitability of this method will be given in the discussion.

Table 3: The PDI for every soil pit. Pit number PDI Pit number PDI Pit number PDI Pit number PDI 1 0.31 10 3.47 19 1.04 28 2.17 2 1.77 11 2.76 20 2.93 29 1.67 3 3.99 12 0.51 21 3.42 30 2.93 4 5.73 13 0.82 22 4.70 31 0.73 5 2.96 14 1.04 23 5.26 32 1.85 6 3.26 15 0.57 24 4.41 33 3.28 7 1.66 16 1.32 25 4.19 34 0.21 8 1.39 17 3.47 26 0.14 9 0.44 18 1.26 27 0.56

Figure 14: The value of the Development Index for every Bw horizon.

In Figure 14 the Horizon Development Index (HDI) for the Bw horizon is plotted. Not every soil pit has a Bw horizon, the soil pits without a Bw horizon were left out of the map. Most of the values are between 0 and 1.5. All of the values on landform 4 are between 0 and 0.75, furthermore the majority of soil pits on landform 5, landform 1 and landforms 2 and 3 have HDI’s between 0 and 1.5. Higher values can be found on landform 7 and the surrounding pits and on landform 6.

Figure 15: pH difference between the Bw horizon and the C horizon (pH_C - pH_Bw).

In Figure 15 the difference in pH between the Bw horizon and the C horizon is mapped. The soil pits without a Bw horizon were left out of the map. The lowest pH differences are found on the end moraines (landform 1), on landforms 2 and 3 and on landform 8. The highest differences are found on landform 5, landform 4 and landform 7. For the majority of the soils pits the difference between the Bw horizon and the C horizon is between 0 and 0.2.

ROCK WEATHERING In Figure 16 the 40 rocks that were used in this research are mapped. In Appendix II the site and surface descriptions and measurements of all rocks can be found.

Figure 16: Map with all the locations of the rocks that were measured.

Figure 17: Average rebound values for the last 20 rocks that were measured.

In Figure 17 the average rebound values for rocks 20 to 40 are mapped. Because the first 20 values were lost not every landform has measurements. There are for example no rebound measurements on landform 1 and only three measurements on landform 4. For the landforms with rebound values there is a variety of values, low and high rebound values can be found on every landform. In Table 4 an overview of the measured rebound values per rock and per landform can be found. Also the average, maximum and median rebound value for every landform is listed in table 4.

Table 4: Average, maximum and median rebound values per landform. Landform Average rebound value Average Max Median 7 50.1 41.7 50.1 41.7 7 33.3 8 42.1 37.2 42.1 36.8 8 37.6 8 33.2 8 35.9 9 32.6 38.8 44.9 38.8 9 44.9 2 37.3 33.0 37.3 33.9 2 27.9 2 33.9 3 34.4 4 39.7 6 42.1 50.7 59.3 50.7 6 59.3 5 49.7 41.6 49.7 41.6 5 33.4

LICHENOMETRY The lichen measurements were done on the same rocks as the rebound measurements, see Figure 16. In Figure 18 ages calculated with the method of (Benedict, 1967) are mapped. The highest values are found on landforms 4 and 1. The relatively freshly deposited rocks have low ages; the rocks behind landform 6 and the rocks above landform 3. On landform 4 both lower and higher ages can be found, which is also true for all the other landforms with exception of landform 1. Landform 1 predominantly has lichens older than 1500 years. In Table 5 the ages of the lichens on landforms 1, 2, 3 and 4 are listed. Landform 1 has the highest average age as well as the highest median. The highest maximum age of 2700 years was found on landform 4.

Figure 18: Age according to (Benedict, 1967) of the biggest R.Geographicum lichen thallus per rock.

Table 5: Ages of the biggest R.Geographicum thalli for multiple rocks on landform 4, 1, 3 and 2. Also the average, maximum and median for every landform is listed. Landform Thallus size (mm) Ages (years) Average Max Median 4 29 500 1163 2700 725 4 32 600 4 95 2700 4 40 850 1 55 1350 1650 2600 1650 1 92 2600 1 85 2350 1 64 1650 1 70 1850 1 50 1200 1 32 600 1 63 1650 1 62 1600 3 37 750 688 750 750 3 36 750 3 29 500 3 37 750 2 38 800 1383 2200 1150 2 48 1150 2 80 2200

Figure 19: Lichen cover (in %) per rock.

In Figure 19 the lichen cover per rock is mapped. The highest lichen coverages are found on landform 7 and the surround rocks, as well as on landforms 1, 2 and 3. The majority of the rocks has a coverage of more than 40 %. The rocks on landform 4, landform 6, landform 10 and the rocks above landform 3 have the lowest lichen coverages.

V Discussion

POST-GLACIAL LANDSCAPE DEVELOPMENT

The retreat of a glacier exposes a landscape that is in an unstable condition (Ballantyne, 2002a). This often results in accelerated geomorphological activity, which is termed paraglacial (Ballantyne, 2002a). (Church and Ryder, 1972) defined the term paraglacial as ‘nonglacial processes that are directly condition by glaciation’. These unstable conditions result in slope failure, debris flow activity and fluvial reworking of sediments (Ballantyne, 2002b). The exposure of glacially steepened rockwalls can result in three different responses (Ballantyne, 2002b): - large-scale rock slope failure, in the form of major rockslides or rock avalanches; - large-scale rock mass deformation, in the form of slow movements; - rapid adjustment of rockwalls by frequent rockfall events, in the form of talus debris at the foot slope.

In the Fourth of July cirque these nonglacial deposits were also observed. With debris flows close to the cirque, talus debris at foot slopes (landforms 2 and 6), slow movements in the form of rock glaciers (landform 11), rockslides (landform 9) and other types of slope failure such as mudflows (landform 3). After the retreat of the Pinedale glacier the Fourth of July cirque area probably was in an unstable condition, which resulted in slope failures. Possibly first more rapid adjustment of rockwalls took place, in the form of rockfall events observed as landform 2 and 6. The other landforms in the area that are a consequence of slope failure can also be the results of slope processes as they occur in every landscape, they are not necessarily paraglacial.

TO WHICH EXTENT CAN THE SOIL DEVELOPMENT INDEX BE USED TO DESCRIBE THE EVOLUTION OF A LANDSCAPE?

Development Index

In Figure 13 the profile development index is mapped and in Figure 14 the horizon development index for every Bw horizon in the study area is mapped. The higher the development index is, the more soil development took place and the older the soil should be. If this hypothesis is correct then the development indices of the soils on the younger end moraines, landform 3 and other slope deposits should have the least development and those that are located on landform 7 and 5 should have the highest indices.

Landform 7 and surrounding landforms The pits on landform 7 indeed have the most development, this is expected because this landform has most probably not been covered by the glaciers of the last 30 000 years in contrast to the rest of the study area. The soil pits located at the foot of landform 7 and higher upslope (pits 20,21,24 and 25) show PDI’s similar to that of the pits on landform 7. These pits also show more development than the pits on landform 5. This suggests that the landforms on which the pits are located have not been glaciated during the last ice ages either. If it is true that this part of the valley has not been covered by the glaciers of the last ice ages, then the landform where soil pits 26, 27 and 28 are located have not been covered by glaciers either

because it has a similar elevation. Topography is the most important soil forming factor for landform 10. Since it has probably not been covered by glaciers but it has a shallow soil with little development, age is not the dominant soil forming factor. Recent deposition of material from upslope is probably the reason for the shallow undeveloped soil. In the field stream patterns on the inside of the landform were visible, which indeed indicate slope processes.

Landform 4 Landform 4 has a HDI between 0.1 and 0.75, the Bw horizons on landforms 2 and 3 also have a HDI in this range. The PDI’s on landform 4 are also similar to the PDI’s on landforms 2 and 3. Nevertheless it is expected that landform 4 is older than landforms 2 and 3. Therefore a relatively small difference in age is expected, which would mean that almost immediately after deglaciation landforms 2 and 3 were deposited.

An exploration of soil forming factors serves to discuss this issue. The five soil forming factors are parent material, climate, topography, vegetation and age. Since the PDI and HDI are comparisons of the soil horizons with the parent material, this soil forming factor can not be the reason for the unexpected results. Climate and vegetation are almost the same for the whole study area. Topography is differing per landform though. Landform 4 is flat and wet, with groundwater on the surface. Landforms 2 and 3 are located on a higher elevation, with steeper slopes and are not as wet as landform 4 is. The small differences in PDI and HDI between landform 4 and landforms 2 and 3 could be due to the difference in topography. Due to the high groundwater table of landform 4, there will be almost no oxidation and the soil can hardly develop.

Landforms 1 and 2 Landform 2 seems to be covered partly by landform 1, although this could not be observed clearly in the field. The age difference according to the PDI and HDI of the Bw horizon between the two landforms is small. This is unlikely since it is not probable that the creation of these landforms in this particular order took place in just a few decades. No clear explanation can be given for this issue. The results could suggest that the age difference between the two landforms is small. It could also mean that another soil forming factor is responsible, but since vegetation, climate and topography are similar and the parent material has been taken care off in the PDI, this is not likely. The explanation could also be sought in the method of Harden, this will be discussed in the comparison with Birkeland.

Landform 5 The pits on landform 5 near the big valley have a Bw horizon development index between 0.34 and 2.22 and a PDI between 1.03 and 3.89. Pits 2, 3, 17 and 18 are located on landform 5 and pits 1, 4, 5, 16, 29, 30, 34 are located on landform 4. Most of the pits on landform 4 do not have a Bw horizon and can therefore not be compared to the pits on landform 5, only pit 29 and 30 have a Bw horizon.

The Bw HDI of the pits on landform 5 have an higher value than the pits on landform 4. Only pit 18 has a lower HDI than both pits on landform 4. The PDI’s of pits 2 and 18 are similar to the PDI’s of the pits on landform 4, while pits 3 and 17 have higher values. It is not expected that landform 4 has more soil development than landform 5 because the lateral moraine is exposed first during deglaciation, followed by landform 4 in front of landform 1. The higher horizon development indices on landform 5 are thus not unexpected.

Surprisingly soil pit 18 on landform shows only little development. This might be due to the location of that particular soil pit. The pit was dug near the crest of landform 5 and it is possible that this was a location with a lot of erosion. With a slope of only 5 degrees it is not probable that water erosion was of significant influence here. There was a mine in the Fourth of July cirque, located on this landform. The transportation to and from the mine probably has something to do with it. The transport would go over the lateral moraine, following the trailhead that is present nowadays. Landform 5 has also been used as a campsite since at least 9500 – 8000 B.P (Birkeland, 1987). It is probable that these activities influenced the soil development on landform 5, which explains the lower than expected HDI and PDI.

Landform 6 Soil pit 33 on landform 6 has a development index that is even greater than that of the soil pits located on landform 7. This could mean that this landform has also not been covered by any glaciers for the past 30 000 years, but the elevation and position in the landscape of the landform make this improbable. A more realistic explanation is that the soil on this landform is inherited from the Quarter to Five peak. The deposits of which the rampart consists came down from the peak and it is possible that not only the rocks but also the soil was translocated and preserved. The glaciers of the last 30 000 years never reached the top of the Quarter to Five peak, this is certain because the Fourth of July cirque is lower. The soil on the peak could therefore be more developed than the soils in the study area. With inheritance of this soil the development does not depicts the time since deglaciation. Therefore, no relative age can be assigned, although it is likely to be post-glacial.

Comparison with literature

(Birkeland et al., 1987) made a chronosequence of alpine soils in the Colorado Front Range. Soil pits were dug and described on parent materials of known age. The parent materials consist of Gannet Peak till deposits, Audubon rock glacier deposit, Triple Lakes rock glacier deposit and Satanta Peak till deposits. He calculated the development of these soils with two different methods, he adjusted the methods as they are described by (Bilzi and Ciolkosz, 1977) and (Harden, 1982). The profile development indices as well as the color indices are listed per soil pit or site in Table 6.

Table 6: Values for soil-profile and color indices of the soils (Birkeland et al., 1987)

The youngest deposits have the lowest development indices while the oldest have the highest development indices, as can be seen in Table 6. The PDI’s with the soil characteristics used in this study have been calculated with the data of (Birkeland et al., 1987). The results of these calculations are listed in Table 7.

Table 7: Values of the PDI of the sites in (Birkeland et al., 1987), calculated according to the method used in this research Site PDI CO2 0,296 CO1 1,008 CO3 6,106 CO4 2,395 CO5 2,436 CO6 3,004 CO7 2,463 CO8 3,884

The PDI’s are not increasing with age as is the case for the indices Birkeland calculated. CO3 has the highest PDI while being of Triple Lakes age. The development of the soils of Satanta Peak age are higher than the development of the Audubon sediments and are varying between 2.40 and 3.90. Calculating the PDI’s with the method used in this research does not yield results similar to the results of (Birkeland et al., 1987).

The method of Birkeland is not described detailed enough to recalculate his results. Although the age trends are different for the two methods, this does not mean that the trends observed in this research are false. The method of Harden has been proven to yield expected soil

chronosequences. It does mean though that trends would be different when the method of Birkeland had been used in this research. Which of the two methods yields the correct relative age trends can not be concluded. Both methods should be applied in a study for comparison before conclusions can be made.

pH difference between the Bw and the C horizon

In Figure 15 the pH in the Bw horizon for every soil pit is mapped. The pH of a soil decreases with age, which means that the bigger the difference between the developed soil and the parent material is, the older the soil is.

The biggest differences in pH between the Bw and C horizon are present at soil pits 22 and 23, these are the pits on landform 7. This is what is expected since landform 7 is the oldest landform in the study area. Locations 2 and 3 also have a reasonable difference in pH between C and Bw horizon, this too is expected since these are the pits on landform 5 near the bigger Fourth of July valley.

Pits 29 and 30 are located on landform 4. These pits should be older than landforms 1, 2 and 3. The pits on landform 4 have higher pH differences than the pits on landforms 1, 2 and 3 and lower pH differences than the pits on landforms 5 and 7. The soil pits on landforms 2 and 3 (6,7,8) have higher pH difference than the soil pits on the crests of landform 1 (11,12,13,14,15), with an exception of soil pit 13. The differences are small though (soil pit 7 only has 0.13 pH difference).

TO WHICH EXTENT CAN THE AMOUNT OF ROCK WEATHERING BE USED TO DESCRIBE THE EVOLUTION OF A LANDSCAPE?

In Figure 17 the rebound values measured with the Silverschmidt are mapped. The higher the rebound value is, the harder the rock is and thus the less weathered the rock is. The weathering of a rock increases with time, so the older the rock is the lower the rebound value is.

Rock 39 can be used as a reference since this rock has been deposited behind landform 6 recently. This is known because all rocks behind the rampart are down the slope of the Quarter to Five peak, they have no lichens at all and it is thus probable that the rocks fell down from the peak recently. The rebound value only confirms this since it is high and the rock shows little to no weathering at all.

One of the first things that stands out is the high rebound value on landform 7. This landform is, as stated before, the oldest landform, so it is strange that one of the highest rebound values is found here. One thing that was noticed during the field research is that rocks with a high content of quartz have higher rebound values, so it could be that this rock has a high content of quartz. The other rock that is measured on landform 7 has a lower rebound value, as is expected.

The rest of the study area shows similar rebound values, see Figure 17. On landform 5, 4, 2 and 3 rocks with similar rebound values are found. An explanation for the small differences and variable rebound values can be that the variable quartz content in every rock in the end determines the average rebound value.

During fieldwork it was noticed that on one rock both high rebound values (around 70) and low rebound values (15 for example) were measured. Since the individual measurements are lost, only the average rebound values can be used in this research. Unfortunately no conclusions can be drawn with only the average rebound values. The difference in rebound values on landform 7 is a good example, but also the similar average rebound values on the landform 5, 4, 3 and 2 show that more information is needed to be able to say anything about the ages of the landforms. One thing that can be concluded though is that age is not the only factor that determines the rock hardness, also quartz content or just the rock composition is an important factor.

TO WHICH EXTENT CAN LICHENOMETRY BE USED TO DESCRIBE THE EVOLUTION OF A LANDSCAPE?

Rhizocarpon Geographicum

In Figure 18 the age of the Rhizocarpon Geographicum is mapped. The older a landform or more particular a rock, the bigger Rhizocarpon lichens can be found. The biggest lichens can be found at the end moraines near the cirque and the smallest are found at landforms 2, 3 and 4. This is exactly the opposite of what is expected, since landform 4 is definitely older than landform 1. Also the lichens found on landform 7 are fairly young (only 1500 years old at max), while actually the oldest lichens are expected here. Also the lichens on rocks above landform 8 are smaller than the lichens on the rocks on landform 8.

There are thus other processes or factors that determine the actual size of the lichens besides age. Moisture, stability of the rock or the surface on which the lichen is growing and length of snow-free growing season have the biggest influence on the actual size of the lichens (Benedict 1967). The growth-curve of the Rhizocarpon Geographicum is accurate up to 3000 years old deposits (Benedict 1967). Since most deposits in the study area are exposed earlier than 3000 Before Present (B.P.), this could be the main reason for the unexpected spatial variation in lichen age. This is especially true for landforms 4, 5 and 7. The more recently active landforms, such as landform 6, show small to no lichens and this is also what is expected.

Landform 10 and 7 On landform 10 a maximum R.Geographicum diameter of 60 mm was found and the lichen cover is ranging from 5-50%. The diameter of 60 mm corresponds to an age of 1500 years according to (Benedict, 1967). The biggest R.Geographicum found on landform 6 is 40 mm and the lichen cover is ranging from 0-10%. But both landforms have not been covered by glaciers for at least the last 3000 years, nothing about the start time of deposition of these landforms can be said on the basis of lichenometry.

Lichen cover

Interesting is the spatial variation of the total lichen cover, as can be seen in Figure 19. The highest lichen cover can be found on landform 7 and the rocks surrounding this hill. The percentage of lichen cover increases with time. The lichen cover does show the older age of the rocks on the hill, which is not observed in figure 18.

Landforms 1, 2, 3 and 4 The lichen cover on the rocks on landform 4 does not differ much from the lichen covers found on landforms 1,2 and 3. The rocks on landforms 1, 2 and 3 have a cover between 40 and 80 % and the rocks on landform 4 have a cover varying between 0 and 80 %. It could be that yearly snow cover on these landforms is of influence on the lichens. With yearly fresh snow some lichens may die which prevents the lichens from covering the whole rock. Without any limiting factors all the rocks on these landforms would probably have a lichen cover between 60 and 100 %, since most lichens are full grown within a few ages.

Comparison with literature

Lichen thalli of different ages were measured by (Benedict, 1968). On a total of 50 moraines lichens were measured, a summary of these results is given in Figure 20.

Figure 20: Maximum diameter R.Geographicum thalli measured on 50 moraines in the Indian Peaks area. The measurements fall into three broad size classes, suggesting three major periods of Little Ice Age glaciation

The three clusters of measurements were interpreted as three glacial advances by Benedict. Deposits of the youngest glacial advance, the Gannet Peak, have a lichen cover of 0-5 % and R.Geographicum thalli are rare with a maximum size of 20 mm. The moraines are fresh and bouldery and are close to the present day glaciers.

Moraines of the glacial advance before the Gannet Peak are hard to distinguish from the Gannet Peak moraines, they are fresh and bouldery with sharp crests and steep slopes. This glacial advance is called the Arikaree stage (1000 – 1900 B.P.) by Benedict, comparable to the Audubon used in this research. Lichen cover of the rocks on the moraines range from 10 to 40 % and R.Geographicum thalli with a maximum size ranging from 42-71 mm.

The oldest glacial advance is called Temple Lake (2900 – 4500 B.P.) by Benedict, in age comparable to the Triple Lakes advance used in this research. Moraines are located 0.1 – 1.3 km down-valley from modern glaciers, are covered with vegetation and have numerous and angular boulders. Lichen covers range from 80 to 95% and maximum diameters of R.Geographicum thalli range from 107 to 150 mm.

Rocks on the moraines (landform 1) in the Fourth of July cirque have a lichen cover ranging from 40-80% and a maximum R.Geographicum thallus size ranging from 40-100 mm. The oldest terminal moraine is located 0.3 km from the ice and snow fields in the cirque and is covered with vegetation.

Although the description of the Temple Lake moraine by Benedict fits the terminal moraine (landform 1) in the Fourth of July cirque the best, there is not a rock anywhere in the study area with R.Geographicum thalli of more than 100 mm. Not even on landform 7, that has not been covered by the Triple Lakes glacial advance, thalli of more than 100 mm have been found.

R.Geographicum thalli are full-grown after approximately 3000 years, they then have a maximum diameter of 110 mm according to the growth curve of (Benedict, 1967). The Temple Lake glacial advance ended around 2900 and the biggest thallus that was found on the end moraines has a diameter of 92 mm which is, according to (Benedict, 1967), equal to 2600 years. The second biggest R.Geographicum thallus has a size of 85 mm, which is equal to approximately 2300 years. The lichen thalli are younger than the Temple Lake but older than the Audubon.

Maximum R.Geographicum diameters of 102 mm on the inner moraine (inner part of landform 1) and 125 mm on the outer moraine (outer part of landform 1) were found by (Mahaney, 1973a). He also found somewhat lower maximum diameters of R.Geographicum thalli than (Benedict, 1968). The Fourth of July cirque is south-facing and according to (Mahaney, 1973a) the growth rate could thus be slightly slower in south-facing positions, as a function of shade and available moisture (Benedict, 1968). In this research smaller diameters were found than (Mahaney, 1973a). Most investigated rocks were either on the ridge of the end moraine or on the inner moraine. The biggest R.Geographicum thallus that was found is 10 mm smaller than the biggest thallus found by (Mahaney, 1973a), which is a small difference.

The lichen cover in the study area is lower than the lichen covers found on Temple Lake deposits by (Benedict, 1968), with values up to 80 %. (Mahaney, 1973a) found lichen covers ranging from 50 to 80 % on the end moraines, which is comparable to what was found in this research.

The end moraine has probably been deposited during the Temple Lake glacial advance, according to the maximum R.Geographicum thalli, the lichen cover and the comparison with (Mahaney, 1973a) and (Benedict, 1968). The biggest thalli on landform 2 are not bigger than 110 mm, with the maximum thallus being 80 mm. The lichen cover is ranging from 50-80%, which is comparable to the lichen cover found on the end moraine. Although field observations point to landform 1 being younger than landform 2, this is not confirmed by the lichen data.

On landform 3 maximum diameters of 37 mm were found and lichen cover was ranging from 20 – 60%. Both from field observations and from lichen data it is clear that landforms 2 and 3 are indeed separated and of different age. Both the lichen cover and the R.Geographicum thalli diameters are comparable to Audubon deposits, both (Benedict, 1968) and (Mahaney, 1973a) found similar values. The age of the mudflow is approximately 700 years according to the growth curve of (Benedict, 1967).

WHAT IS THE GEOMORPHOLOGICAL HISTORY OF THE LANDSCAPE IN THIS STUDY?

The retreat of the Pinedale glacier first exposed landforms 5 and 8. Landform 8 has characteristics of a moraine but because of the relatively high and steep slope it could not be concluded what this landform actually is. After further retreat of the glacier landform 4 was exposed, this landform is a ground moraine. Around 13 ka B.P. the Pinedale glacier was probably almost completely retreated and maybe only present in the cirque itself. The deglaciation caused unstable conditions and slope failures were the result of this. Landforms 2 and 6 were deposited because of these slope failures. A glacial advance from 5 200 to 3 000 years B.P. (Triple Lakes) probably deposited landform 1, which is a terminal moraine. Closer to the cirque multiple smaller terminal moraines can be found, probably as a result of the glacial advances that followed after the Triple Lakes (the Audubon and the Gannett Peak). Some younger landforms were deposited by slope processes after the Triple Lakes glacial advance.

A summary of the geomorphological history of the Fourth of July cirque can be found in table 8. The landform, type of landform, relative age, estimated absolute age and the confirmation of the relative ages by the three relative dating methods are listed.

Table 8:Summary of the geomorphological history of the Fourth of July cirque. The determined type of deposit, relative age and estimated absolute age and their confirmation by each of the three relative dating techniques Relative Estimated absolute age Soil Rock Landform Type of deposit age (ka) dating weathering Lichenometry 7 Bedrock hill 8 > 30 + - - 5 Lateral moraine 7 13-23 + - - 8 - 6 13-23 - - - Ground 4 moraine 5 13-23 - - - 2 Rampart 4 5-13 - - - Protalus 6 rampart 4 5-13 - - - 3 (oldest), 0.1 - 0.35 1 End moraines 3 (youngest) + nd + 3 Mudflow 2 1 + - + 9 Blockflow 2 1 + - + 10 - 1 0 - 1 + nd + Active rock 11 glacier 1 0 - 0.2 nd nd nd

VI Conclusion

The geomorphological history of the Fourth of July cirque could be described roughly with the use of field reconstruction, soil dating and lichenometry. The glacial landforms became exposed with the retreat of the Pinedale glacier. The unstable conditions of the landscape caused by the deglaciation resulted in slope failures. Minor glacial advances that followed after the Pinedale glaciation deposited multiple terminal moraines. Younger landforms were deposited by slope processes.

The extent to which soil dating, lichenometry and rock weathering could be used to describe the geomorphological history of the Fourth of July cirque differs. The calculated soil development indices represent the actual relative ages of the landforms fairly good in 6 out of the 10 landforms. Rock weathering could unfortunately not be used to come to a relative age distribution of the landforms. This was mainly due to problems with the equipment. Lichenometry was useful for determining relative ages for the younger landforms. Since most landforms are older than the lifespan of the R.Geographicum species, this method could not be used for these landforms.

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Appendix I: Soil site and surface descriptions

34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 number Pit Lower down the valley on flat, wet part wet on (ground-moraine) flat, valley Lower the down On protalus rampart ground/lateral-moraine On possible ground moraine Right side ground-moraine the of On slope 26, pit of Lower on landform the on almost ridge/crest the glacier end-moraine/rock Within glacier end-moraine/rock On possible 24) (pit moraine lateral above On slope the rock (end-moraine??) glacier On possible bedrock hill Crest the of bedrock hill the of Lower slope ground moraine on possible the Further up-slope age Pinedale ground of moraine possible of Mid slope near Nederland end-moraine Pinedale moraine on crest the lateral the of Almost moraine crest the lateral the of Just below moraine) (ground foot area flatter on end-moraine the wetter, Lower, and more higher on left the moraine, Crest the of asmoraine old the describes On backthe what of Williams and more higher on left the moraine, Crest the of moraine of Slope moraine of Crest/top end-moraine behind Depression rockabove glacier on mudflow up slope higher rockabove glacier mudflow of On slope top outer ring the of rockof end Left glacier/mudflow, on top outer ring of rockthe of glacier/mudflow, middle In the partOn top higher ground of the of moraine part towards higher ground the On of moraine slope Pinedale Near moraine crest lateral Pinedale moraine lateral Footslope Ground moraine Landform x GPS coördinates 443856 443744 444046 443986 443937 443855 444179 444263 444265 444379 444297 444189 444174 444219 444132 455543 444110 443853 443833 443830 443937 443872 443872 443918 443920 444028 443962 443902 443933 443911 443812 443674 443732 443748 y 4429164 4429418 4429289 4429285 4429243 4429256 4429381 4429416 4429398 4429297 4429318 4429229 4429248 4429338 4429296 4423144 4428869 4429086 4429461 4429680 4429680 4429635 4429573 4429570 4429600 4429508 4429463 4429433 4429395 4429338 4429322 4429299 4429323 4429324 ? (degree) slope 29 23 13 17 21 23 14 18 12 10 35 18 10 17 10 11 2 0 7 6 4 9 5 5 4 0 0 0 9 6 2 0 grass and mosses grass and mosses meter a few within all shrubs pines and grass, small mosses, grass, some shrubs pines, mosses weeds, shrubs, pines, and mosses pines weeds, grass and mosses and grasssome mosses grass/moss little grass and mosses grass and mosses grass and mosses some shrubs grass,and small mosses short shrubs on grass,2 pine and m shrubs some dist. 10 short within grass, short m pines grasstrees and pine grass and mosses grass,and weeds mosses small grass and shrubs grass and grasssome mosses grass and mosses grass and mosses grass and mosses grass on atrees short pine distance grasssmall with shrubs grasssmall some with grass and mosses to grasses shrubs close shrubs and mosses a shrubs of and lot grasses (35%)some vegetation shrubs and low some grass grass vegetation 100 50 90 50 60 60 70 60 20 80 50 80 70 60 60 50 50 100 90 90 100 70 100 70 80 80 80 90 100 100 45 cover (%) 100 80 230 110 270 260 - 200 230 230 240 250 230 230 310 230 260 160 54 250 110 16 - 210 - - 210 225 240 170 ? 290 80 - aspect 80 straight concave straight straight flat concave convex straight crest convex concave crest concave convex straight convex convex straight straight convex convex convex convex - concave convex convex straight straight concave concave concave - profile curvature straight straight straight straight flat straight convex straight crest convex straight crest straight straight convex straight convex straight ? convex convex convex convex - convex convex convex convex straight concave straight straight - plan ------stream incision ------away flushed material fine water, of incision - area the spread over water flows cutting small of some - - type features erosion 0 90 30 70 20 comments) (see 10 40 60 80 40 20 30 comments) (see 30 comments) (see 35 comments) (see 20 comments) (see 5 5 comments) 5 (see 30 50 comments) (see 30 30 40 10 20 20 25 20 0 0 20 cover (%) surface stoniness 15 0 S/B S/B (Stones/boulders)??? - boulders) gravels F-B (fine S/B (Stones/boulders) S (stones) C (coarse gravels) and boulders) S-B (stones C (coarse gravels) - boulders) gravels F-B (fine S (stones) S/B (Stones/boulders) S (stones) S (stones) and C/S (coarse gravel stones) - stones) gravel (Fine F-S S (Stones) S (Stones) S/B (Stones/Boulders) S/B (Stones/Boulders) S/B (Stones/Boulders) and boulders) stones G/S/B (gravel S and - Bboulders) (Stones S and - Bboulders) (Stones > 200 >10 > 20 (20F-S - 50) - - gravel) gravel/Medium F/M (Fine S/B (Stones/Boulders) - (cm) size

Appendix II: Rock site and surface descriptions and measurements

Pit number Pit 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 further down down further of on slope protalus behind the of on ridge on ground 20 from meters on top side left on outer ring top on right side, not the in on landform middle on slope, towards on edge on lower part on higher on more left On landform from looking on also bedrock on top the of part low of up the higher and Higher more to big next right, on talus big the of middle on just top of Upper mudflow as same moraine on right side lower on inner, the down top of left higher more left higher, top end- of end- of middle on end-moraine, end- under on right side ground- slope Landform GPS x 443976 443694 443726 443744 443843 443968 443924 443914 443949 443942 443987 444092 444130 444189 444239 444294 444291 444241 444181 444216 443966 444245 444166 444111 444074 444017 444045 444064 443963 443903 443849 443865 443834 443856 443898 443935 443977 443805 443937 443855 GPS y 4428986 4429307 4429428 4429418 4429455 4429486 4429474 4429403 4429402 4429270 4429284 4429316 4429329 4429327 4429351 4429313 4429281 4429281 4429228 4429234 4429463 4429396 4429386 4429411 4429485 4429519 4429532 4429559 4429664 4429688 4429688 4429738 4429774 4429684 4429598 4429552 4429587 4429437 4429243 4429256 rock volumerock (m3) 0.125 0.72 9.72 1.35 1.25 2.25 2.88 0.15 2.25 22.5 21.6 0.5 0.5 0.5 0.6 0.5 2.5 5.4 0.5 4.5 4.5 0.8 72 18 18 27 15 12 42 54 15 36 45 3 1 4 6 6 gneiss ? white very granite granite gneiss granite granite gneiss, but banded (banded) gneiss gneiss granite gneiss gneiss or granite gneiss granite ? granite granite granite..? gneiss, ? of (lots granite granite granite granite gneiss biotite granite? granite granite granite granite gneiss biotite granite granite with granite granite with granite ? granaat biotite acid biotite Rock type All lichens cover (%) All lichens cover 60 30 35 70 65 50 80 50 40 10 80 70 60 90 70 90 90 80 70 70 50 30 55 60 25 20 70 65 55 60 40 85 55 80 60 45 50 30 0 5 RG (%) cover 50 20 10 10 10 10 10 10 10 10 15 50 30 30 20 20 10 10 10 30 25 25 15 15 20 20 10 10 40 15 10 0 5 5 5 3 5 5 4 7 (mm) diameterAverage 26.80 38.20 31.25 23.20 32.00 58.40 37.80 34.00 45.40 20.40 40.80 43.00 25.60 36.40 37.00 41.60 34.00 32.50 46.00 41.00 37.40 34.20 42.80 39.80 26.40 27.00 29.67 50.20 49.80 25.20 33.40 49.17 44.67 60.78 59.60 49.00 50.63 19.43 24.57 St.Dev (mm) 11.81 10.80 15.18 15.61 10.93 10.57 12.46 10.09 11.14 16.88 19.82 19.50 27.96 5.17 7.22 5.70 5.81 3.94 8.56 6.47 5.10 5.13 5.59 4.36 5.37 5.66 9.00 7.21 8.62 6.38 1.95 9.26 5.89 7.16 9.88 5.89 4.64 8.42 3.31 Max diameter (mm) 33.00 50.00 40.00 40.00 37.00 80.00 48.00 38.00 57.00 29.00 65.00 49.00 31.00 45.00 42.00 47.00 40.00 40.00 60.00 50.00 47.00 40.00 60.00 55.00 29.00 36.00 37.00 62.00 63.00 32.00 50.00 70.00 64.00 85.00 92.00 55.00 95.00 32.00 29.00 Min diameter (mm) 21.00 32.00 15.00 15.00 24.00 40.00 34.00 28.00 35.00 11.00 28.00 38.00 19.00 30.00 32.00 35.00 25.00 20.00 35.00 30.00 29.00 25.00 34.00 27.00 24.00 14.00 22.00 44.00 40.00 18.00 24.00 40.00 16.00 40.00 47.00 43.00 20.00 11.00 20.00 Age (y) Age 1200.00 2200.00 1133.33 1433.33 1700.00 1166.67 1033.33 1100.00 1533.33 1200.00 1100.00 1533.33 1366.67 1600.00 1633.33 1200.00 1866.67 1666.67 2366.67 2600.00 1366.67 2700.00 633.33 866.67 866.67 766.67 800.00 500.00 566.67 933.33 866.67 866.67 866.67 500.00 733.33 766.67 600.00 600.00 500.00 SH_X av 33.4 49.7 59.3 42.1 39.7 34.4 33.9 27.9 37.3 44.9 32.6 35.9 33.2 37.6 38.7 43.2 33.4 42.1 33.3 50.1 SH points # of 19 15 15 20 15 30 30 15 30 30 15 30 30 15 15 15 15 15 15 30 SH St.dev 10.2 13.9 12.5 16.0 12.9 14.5 13.5 12.4 15.2 13.6 11.6 11.2 14.3 12.4 11.8 11.5 10.2 13.2 12.5 14.3 SH_X (N/mm2) av 14.0 30.0 47.5 24.0 18.5 13.7 14.0 10.5 16.5 24.0 13.0 15.5 13.5 17.0 18.0 22.0 14.0 21.0 13.5 30.5

Appendix III: Overview of soil characteristics, PDI and HDI values

horizon color Pit nr horizon color hue color value structure depth (cm) chroma pH OM content (%) HDI PDI 1 H 0 - 10 5y 2 1 clods 4.46 68.88 0.42 0.42 1 Hr 10 - 43 10yr 2 2 clods 4.64 33.90 0.00 0.42

Ah 0 - 6 10yr 2 2 Moderate granular 2 4.18 31.81 0.83 1.56

Bt 6 - 16 10yr 4 3 Moderate granular 2 4.72 5.30 0.73 1.56

C 16 - 43 10yr 4 2 Weak granular 2 5.02 1.90 0.00 1.56 3 Ah 0 - 5 5yr 2 1 Single grain 4.54 24.83 0.77 4.05

Bw1 5 - 20 10yr 3 4 Weak granular 3 3.88 5.89 1.29 4.05

Bw2 20 - 35 10yr 4 4 Weak granular 3 3.85 8.13 0.89 4.05

BC 35 - 50 10yr 4 4 Moderate granular 3 3.81 6.63 1.09 4.05 4 Oi 2 - 0 - 0.00 6.49 4 Ah1 0 - 16 7.5yr 2 0 Single grain 4.73 29.52 2.65 6.49 4 Ah2 16 - 40 5yr 2 1 Weak granular 4.83 40.54 3.84 6.49 5 Ah 0 - 20 10yr 2 2 Single grain 5.25 51.92 1.56 3.38 5 C1 20 - 72 10yr 2 2 Weak granular 4.32 26.35 1.81 3.38 5 C2 > 72 10yr 3 4 Single grain 4.93 10.29 0.00 3.38 6 Ah 0 - 22 7.5yr 2 0 Single grain 5.44 22.82 3.39 3.82 6 Bw 22 - 35 7.5yr 4 3 Moderate granular 5.24 5.59 0.43 3.82 6 C 35 - 69 10yr 4 3 Moderate granular 5.19 3.90 0.00 3.82 7 Ah 0 - 8 5yr 2 2 Single grain (OM) 6.03 16.57 0.71 1.57 7 Bw 8 - 25 7.5yr 4 2 Weak granular 4.25 6.51 0.86 1.57 7 C 25 - 55 10yr 4 3 Weak granular 4.38 5.33 0.00 1.57 8 Ah 0 - 11 10yr 2 2 Weak granular 5.05 13.53 0.79 1.83 8 Bw 11 - 30 10yr 3 3 Weak granular 4.32 4.74 1.03 1.83 8 C 30 - 59 10yr 3 4 Weak granular 4.70 3.20 0.00 1.83 9 Ah 0 - 15 10yr 3 2 Single grain 4.83 9.92 0.16 0.60 9 Bw 15 - 36 7.5yr 4 2 Weak granular 4.21 5.17 0.44 0.60 9 C 36 - 50 10yr 3 3 Moderate granular 3.96 3.41 0.00 0.60 10 O 1 - 0 0.00 3.81 10 Ah 0 - 16 10yr 3 1 Single grain (OM) 3.75 23.62 1.23 3.81 10 Bw 16 - 35 10yr 3 3 Moderate granular 3.91 8.56 2.58 3.81 10 C 35 - 60 10yr 3 3 Single grain (sand) 4.34 1.77 0.00 3.81 11 Ah 0 - 10 10yr 3 3 Single grain (OM) 4.53 16.28 0.39 2.50 11 Bw 10 - 45 5yr 3 3 Weak granular 4.52 7.05 2.11 2.50 11 C > 45 10yr 4 4 Weak granular 4.31 5.02 0.00 2.50 12 Ah 0 - 10 10yr 2 1 Single grain 5.29 10.14 0.50 0.82 12 Bw 10 - 20 10yr 3 2 Weak granular 5.08 5.90 0.33 0.82 12 C 20 - 50 10yr 3 3 Weak granular 4.52 4.28 0.00 0.82 13 Ah 0 - 13 10yr 2 2 Single grain 4.70 27.00 0.92 1.20 13 Bw 13 - 23 10yr 3 3 Weak granular 4.77 8.76 0.28 1.20 13 C 23 - 40 10yr 3 4 Weak granular 5.07 6.55 0.00 1.20 14 Ah 0 - 12 10yr 2 2 Single grain (OM) 4.86 21.23 0.81 1.17 14 Bw 12 - 24 10yr 3 3 Weak granular 4.01 6.27 0.36 1.17 14 C 24 - 37 10yr 4 3 Weak granular 4.03 4.74 0.00 1.17

horizon color Pit nr horizon color hue color value structure depth (cm) chroma pH OM content (%) HDI PDI 15 Ah 0 - 14 10yr 2 2 Single grain (OM) 5.38 20.81 0.55 0.55 15 Bw 14 - 22 10yr 3 4 Weak granular 4.99 7.65 0.00 0.55 15 C 22 - 35 10yr 3 3 Weak granular 4.99 6.74 0.00 0.55 16 H1 0 - 10 5yr 2 2 Peat 6.11 61.66 0.50 0.90 16 H2 10 - 20 10yr 3 3 Peat 4.79 59.05 0.00 0.90 16 C1 20 - 38 10yr 2 2 Moderate granular 3.80 15.25 0.40 0.90 16 C2 38 - 50 10yr 5 8 Structureless 3.96 9.31 0.00 0.90 17 Ah 0 - 16 10yr 3 2 Weak granular 3.67 10.45 1.59 4.11 17 Bw 16 - 45 10yr 3 3 Weak granular 3.70 4.84 2.52 4.11 17 C 45 - 51 10yr 4 4 Weak granular 4.15 2.86 0.00 4.11 18 Ah 0 - 12 10yr 2 2 Single grain (OM) 4.27 9.84 0.94 1.28 18 Bw 12 - 34 7.5yr 4 4 Weak granular 3.91 4.62 0.34 1.28 18 C 34 - 41 10yr 4 4 Weak granular 4.00 2.55 0.00 1.28 19 Ah 0 - 10 10yr 3 4 Weak granular 5.30 4.35 0.72 0.72 19 Bw 10 - 40 10yr 4 3 Single grain 4.81 1.39 0.59 0.72 19 C > 40 2.5y 4 3 Single grain 4.97 1.49 0.00 0.72 20 Ah 0 - 12 7.5yr 2 0 Single grain (OM) 4.54 10.41 1.58 3.30 20 Bw 12 - 55 10yr 3 4 Weak granular 4.30 2.73 1.72 3.30 21 Ah ? 10yr 2 1 Single grain (OM) 3.71 14.09 2.65 4.65 21 Bw ? 10yr 3 2 Weak granular 4.31 3.07 2.00 4.65 22 Ah 0 - 16 5yr 2 1 Single grain (OM) 23.15 1.76 4.47 22 Bw 16 - 45 5yr 3 4 Weak granular 3.65 6.74 2.71 4.47 23 Ah 0 -12 5yr 2 2 Single grain (OM) 4.72 18.46 1.19 4.81 23 Bw1 12 - 20 5yr 3 2 Weak granular 3.97 5.96 0.81 4.81 23 Bw2 20 - 41 5yr 3 4 Weak granular 3.80 6.37 2.82 4.81 24 0 - 14 10yr 2 1 Single grain (OM) 4.81 19.89 1.55 5.28 24 Bw 14 - 55 7.5yr 3 2 Weak granular 4.35 8.87 3.73 5.28 25 1 Ah 0 - 2 10yr 2 1 Single grain (OM) 0.18 5.08 25 1 Bw 2 - 10 10yr 2 2 Weak granular 0.63 5.08 25 2 Ah 10 - 25 10yr 2 1 Single grain (OM) 4.14 22.15 2.31 5.08 25 2 Bw1 25 - 43 10yr 3 4 Weak granular 4.54 6.54 0.91 5.08 25 2 Bw2 43 - 60 10yr 3 3 Weak granular 4.49 6.17 1.05 5.08 26 Ah 0 - 5 10yr 3 2 Weak granular 0.14 0.14 26 C 5 - 30 10yr 4 2 Weak granular 4.69 2.33 0.00 0.14 27 Ah 0 - 8 10yr 2 2 Single grain (OM) 3.48 12.16 0.65 0.65 27 C 8 - 23 10yr 3 3 Single grain (sand) 3.82 4.95 0.00 0.65 28 Ah 0 - 14 10yr 2 2 Single grain (OM) 4.51 16.20 1.41 2.46 28 Bw 14 - 30 7.5yr 4 3 Weak granular 4.10 6.70 1.06 2.46 29 Ah 0 - 12 10yr 2 2 Weak granular 3.76 12.63 1.18 1.80 29 Bw 12 - 20 7.5yr 3 2 Weak granular 3.80 7.98 0.62 1.80 29 C 20 - 30 10yr 4 3 Weak granular 4.29 2.53 0.00 1.80 30 Ah 0 - 10 10yr 2 2 Single grain (OM) 3.81 31.92 1.06 3.39 30 Bw1 10 - 24 10yr 4 3 Moderate granular 3.37 5.64 1.66 3.39 30 Bw2 24 - 33 7.5yr 4 2 Weak granular 3.54 5.79 0.67 3.39 31 Ah 0 - 5 10yr 2 2 Weak granular 3.13 17.72 0.83 0.83 32 Ah 0 - 20 10yr 2 1 Single grain (OM) 4.15 17.08 1.77 2.61 32 Bw 20 - 32 7.5yr 4 2 Weak granular 4.57 4.13 0.83 2.61 32 C 32 - 43 10yr 3 4 Single grain (sand) 4.65 3.66 0.00 2.61 33 Ah 0 - 2 10yr 2 1 Single grain (OM) 0.16 3.82 33 Bw 2 - 49 10yr 3 2 Weak granular 3.94 11.17 3.66 3.82 33 C 49 - 72 10yr 4 3 Weak granular 4.23 5.16 0.00 3.82 34 H 7.5yr 4 2 none (peat) 4.92 77.94 0.07 0.27 34 HC 10yr 3 2 none (peat) 4.97 44.01 0.20 0.27 34 C 2.5yr 4 2 weak massive (see comments) 4.68 3.08 0.00 0.27